DataGridView with unbound field

I have a DataGridView on a form.  I would like this DataGridView to be populated with 4 Fields.
1. Posted
2. Invoice #
3. Invoice Date
4. Total

The last three fields invoice #, Invoice Date and Total are all stored in the invoices Table but my first field which I added is not stored anywhere.  Posted is a check box field in the datagridview.

I also have a submit button.  I would like to be able to check the posted field in the datagridview and when I click on the submit button copy the rows where posted = true to another table.  How can I accomplish this?

I have the datagridview all created with the posted field but that is as far as i got.

Should I create a datatable with matching schema of the datagridview and then somehow populate that? or should I bind the datagridview to my invoices table?  if i bind my datagridview to my invoices table then how do i detect the posted field?